1. Technical Field
The present invention relates to a heat conduction board and a mounting method of electronic components.
2. Background Art
In recent years, high efficiency and high density mounting for electronic components, such as a semiconductor device, are required for high performance and miniaturization of an electronic apparatus, and miniaturization and high density mounting for a circuit board which mounts various kinds of the electronic components are required. Then, a development of a module which unified a power semiconductor device, such as a switching device, and a control circuit which controls it, and advanced radiation property is performed.
Japanese Patent. Application Laid-Open No. 11-233712 discloses an electronic apparatus that a power semiconductor device, and a printed circuit board which has arranged control circuits with high density are mounted respectively on lead frames. These lead frames are arranged on a heat sink on both sides of a resin layer, and is covered by using a resin. A power semiconductor device and the printed circuit board which mounts on the lead frame are electrically connected using conductive wires.
Japanese Patent Application Laid-Open No. 2008-21819 discloses an electronic apparatus provided with a metal plate with opening, a heat conduction resin layer, a lead frame, a power device and a control part. The lead frame is arranged on the resin layer which is arranged on the metal plate. The power device is arranged on the lead frame and is electrically connected therewith. Therefore, the resin layer and the lead frame are located between the power device and the metal plate. The control part is mounted on a printed circuit board, and is arranged at the opening of the metal plate. Therefore, the printed circuit board and the resin layer are located between the control part and the lead frame. At this time, the printed circuit board is electrically connected with the lead frame by a number of pins which passes through the resin layer. Thereby, the wire length which connects with the power device and the control part becomes short, and the influence of noise decreases.
Moreover, Japanese Patent Application Laid-Open No. 2008-210920 discloses a circuit module provided with a metal plate, a heat conduction layer, a lead frame, a printed circuit board, a power system electronic component and a signal system electronic component. The heat conduction layer, the lead frame, and the printed circuit board are arranged on the metal plate in this order. The printed circuit board is provided with a number of openings. The lead frame located in the opening makes a same surface as a mounting surface of the printed circuit board. And the power system electronic component which needs heat dissipation and mounts at the lead frame side, and the signal system electronic component which needs high density mounting and mounts at the printed circuit board side. Thereby the wire length which connects the power system electronic component and the signal system electronic component becomes short, and the influence of noise is reduced.
However, Japanese Patent Application Laid-Open No. 11-233712 has a disadvantage to which a paste resin and a wire-bonding process are required, and the influence of noise becomes severe, since a wire length which connects the electronic component of the power system and the electronic component of the signal system becomes long. On the other hand, Japanese Patent Application Laid-Open No. 2008-21819 and Japanese Patent Application Laid-Open No. 2008-210920 have advantage to which the wire length becomes short, since the electronic components of the both system are directly mounted on the lead frame so that the almost same surface may be formed. Therefore, the influence of noise is reduced. However, since the electronic apparatus of Japanese Patent Application Laid-Open No. 2008-21819 and Japanese Patent Application Laid-Open No. 2008-210920 can mount an electronic component only in one surface of a printed circuit board, high density mounting of an electronic component cannot be performed.